Abstract
A mathematical model to predict the effect of laser and tissue parameters on the zone of thermal injury by laser interaction on beef liver is presented. The heat transfer and coagulation process was modeled using a non-linear finite-element model. The light distfibutionwasmodeledusinganapproximationofthelightdiffusion theory. Thermal feedback allowed for constant surface temperature conditions using a modulated laser source term. A two-layered set-up of gel and tissue allowed for comparing our results with previous experiments carried out under similar conditions. Variations of the damage coefficients and absorption coefficient about their reported and calculated values indicate their sensitivity on coagulation effects based on the Arrhenius rate model. The constant surface temperature provided a control over the coagulation procedure, allowing a slow, steady damage front progression. The parametric study of variations in the damage rate coefficients, laser spot-size and absorption coefficient in this study indicate a significant variation in predicting the coagulation behavior of the tissue. Accurate knowledge of the optical properties and kinetic rate constants is essential for mathematical models to predict reliable outcomes.
Tolat, Nimish Prabodh (1997). Finite element analysis of controlled laser coagulation experiments. Master's thesis, Texas A&M University. Available electronically from
https : / /hdl .handle .net /1969 .1 /ETD -TAMU -1997 -THESIS -T647.